JPS59141255A - Ebullition-cooling type electric apparatus - Google Patents

Abstract

PURPOSE:To inhibit an electric field in bubbles to a sufficiently low value, to increase insulating strength and to apply an electric apparatus easily to specifications at high voltage by providing a conductive shielding plate disposed so as to flow bubbles between the shielding plate and the surface of a heat generating section. CONSTITUTION:Conductive shielding plates 21, 22 are constituted by metallic films 23, 24 electrically connected to the winding-starting and winding-ending sections of coils 15, 16 and heat-insulating plates 25, 26. Flow paths 27, 28 in which bubbles 12 flow are formed among the conductive shielding plates 21, 22 and the surfaces of both coils 15, 16. The potential of the metallic films 23, 24 is each kept at approximately the same potential as the surface of the coils 15, 16, and an electric field is applied only to a refrigerant liquid 4 between the conductive shielding plates 21, 22. Boiling is not generated in the refrigerant liquid 4 in a section where the electric field is applied, the high dielectric strength of the liquid can be utilized effectively while the electric field is hardly applied to the refrigerant liquid 4 and bubbles 12 in a section where a boiling and a heat transfer are executed, and insulating performance as a transformer is not damaged.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an evaporative cooling type electrical device, and particularly to a configuration of a high voltage electrical device such as a transformer employing the evaporative cooling method.

As an example of this type of conventional evaporative cooling type electrical equipment, a case where it is applied to a transformer will be described with reference to FIGS. 1 and 2.

FIG. 1 is a diagram showing its overall configuration, and Figure 2 is an enlarged view of its main parts. In the figure, (1) is at the top,
A closed container with a condenser (3) fitted with radiation fins (2), (4) is a condensable refrigerant liquid contained in the closed container (1), for example C5FlsO (par 70 logyl tetrahydro 7 run). etc. are used, and the liquid surface is occupied by its vapor (4a).

(5) The transformer body is immersed in the tri refrigerant liquid (4), and the high-voltage coil (6) is the main heat generating part to which voltage is applied.
and gate pressure coil (7), insulation barrier (8) interposed between both coils (6) <7) and both coils (6)' (
This is a through terminal that is pulled out of the installation device (1) so as to be interlinked with 7).

Next, the cooling operation of the conventional evaporative cooling transformer configured as described above will be explained. First, in a cold state when the transformer is not operating, when the refrigerant liquid (4) in the closed container (1) becomes saturated at the ambient temperature, copper loss and iron loss occur, respectively, and the temperature begins to rise. . Both coils (6)
(7) and the iron core (9) are immersed in the refrigerant liquid (4), so the refrigerant liquid (4) in contact with their surfaces generates bubbles (12) consisting of its vapor, and both coils (6) ( 7)
And so-called boiling heat transfer, which removes latent heat of vaporization from the iron core (9), is started. The vapor (4a) of the refrigerant liquid (4) is indicated by the arrow (13
), it rises and enters the condenser (3), condenses and liquefies on its inner wall, and then flows downward as shown by the arrow (14) to become refrigerant liquid (4) and is used for cooling again. Ru. After this, the heat of condensation is radiated to the atmosphere through the radiation fins (2). The above phenomenon reaches a certain equilibrium state depending on the conditions of heat generation and heat radiation, and the operation of the transformer is maintained at a predetermined temperature rise.

However, the conventional boiling-cooled transformer as described above has serious drawbacks, particularly in terms of insulation strength. That is, the refrigerant liquid (4), such as the above-mentioned Cs B' lsO, has a dielectric strength of about 70 KV/2.5 tm in liquid form, and has a Re almost equivalent to insulating oil such as mineral oil used in general transformers. However, in the vaporized state, the dielectric strength decreases to the same level as that of air.Especially in the range where the temperature is low immediately after the start of operation, the vaporization pressure (vapor pressure) is low and the dielectric strength decreases extremely. Furthermore, the relative permittivity within the bubble (12) is approximately 1.
．． 0, which is smaller than that of the refrigerant liquid (4) by about 1.9, and the electric field within the bubble (12) increases by that amount, making the decrease in dielectric strength due to boiling even more remarkable. As a result, in coil L6) (7), which has a high heat generation density, generates a large amount of bubbles (12), and has a high applied electric field, the decrease in dielectric strength becomes a problem, and the partial daughter voltage during transformer operation becomes a problem. It was difficult to apply this cooling method to high-voltage transformers, etc., due to an abnormal increase in wear and, in some cases, complete circuit failure.

This invention was made in order to eliminate the drawbacks of such conventional tubes, and is arranged to be electrically connected to the surface of the heat generating part and to allow air bubbles to flow between the surface of the heat generating part and the surface of the heat generating part. The purpose of the present invention is to provide a boiling-cooled electric meter that suppresses the electric field within the bubble to a sufficiently low level by providing a conductive shield plate, has high insulation strength, and is easy to apply to high voltage specifications. .

DESCRIPTION OF THE PREFERRED EMBODIMENTS A boil-cooled transformer according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is an enlarged plan view of a part of the high-low voltage coil opposing portion.

In the figure, a condensable refrigerant liquid (4), an insulation barrier (8),
Since the bubbles (12) are the same as in the conventional case, their explanation will be omitted. (15) and (16) are respectively strand insulation (17)
High-voltage coils and low-voltage coils constructed by winding conductors (19) and (20) subjected to (18), (21) and (22).
) are the high voltage coil (15) and the low voltage coil (16), respectively.
) on the opposite sides of both coils (15) and (16).
One potential part on the surface of (16) (normally both coils (15) (
16)) and the metal films (23) (24) electrically connected to the coils (23) (24) by insulated wires (not shown), etc., and both coils of these inner metal F4 films (23) (24). (15
) (16) It is composed of heat insulating plates (25) (26) consisting of breath plates etc. arranged in contact with the side surfaces.

Then, a predetermined flow rI! in which air bubbles (12) flow between the conductive shield plates (21) (22) and both coils (15) (16) R! r(27) (28) are formed. Note that the spacing between the flow paths M (27) and (28) is related to the heat generation rate and height of both coils (15) and (16), but usually about 1+o+ is sufficient, and the spacing provided at an appropriate pitch is sufficient. ′! /'' (not shown) to secure and maintain the spacing. Also, the metal film (23
) For (24), stainless steel wire mesh or the like is usually used to sufficiently reduce eddy current loss due to leakage magnetic flux.

Next, the operation of the evaporative cooling type transformer as an embodiment of the present invention constructed as described above will be explained with reference to FIGS.
Figure 6 will be explained. Fig. 4 and Fig. 5 show the refrigerant liquid (4) between both coils (15) (16) corresponding to Fig. 3.
FIG. 6 is a diagram showing the temperature and potential distribution, respectively, and FIG. 6 is a diagram showing the relationship with the Ia phase vapor pressure temperature of the refrigerant liquid (4). First, considering the cooling state as in the past, the refrigerant liquid (4
) has a constant distribution with respect to the ambient water temperature TO shown in Figure 6, and the pressure inside the closed container (1) varies from the saturated vapor pressure time S of the refrigerant liquid (4) to the saturated vapor pressure with respect to the temperature TO. It is kept in PO. That is, at this point, the refrigerant liquid (4) and the vapor (
4a) and the pressure POK is maintained together. However, in the description of this invention, the pressure due to the lift of the refrigerant liquid (4) itself is ignored as it is small. Here, when the transformer starts operating and the temperature of both coils (15) (16) starts to rise, the temperature of the refrigerant liquid (4) in contact with the surface of both coils (15) (16) also increases accordingly. As the saturated vapor pressure becomes higher than PO, the pressure balance with the surroundings is broken at this part, and finally a boiling state accompanied by foaming occurs, which contributes to boiling heat transfer and increases the pressure of steam (4a). act. Next, a certain period of time has passed t! i. Consider a state in which thermal equilibrium has been reached. In Fig. 4 and Fig. 6, the refrigerant liquid (4) in contact with the surfaces of both coils (15) and (16), which usually has the maximum heat generation density at the highest temperature of the refrigerant liquid (4)
This applies to the temperature of T2 is the lowest temperature of the refrigerant liquid (4), which corresponds to the temperature of the refrigerant liquid (4) immediately after being condensed by condensation a (3). Therefore, the refrigerant o, (4) is distributed in the overall temperature range of 1 dTl to T2,
The boiling generation distribution is determined from the relationship between this temperature distribution and the saturated vapor pressure characteristic S.

That is, the pressure determined from the characteristic S is determined for the temperatures TI and T2, and naturally the relationship of Pl)Pt2)P2 holds true.

Therefore, the part of the refrigerant liquid (4) whose temperature is higher than the temperature T12 corresponding to PI3 causes boiling, but conversely, the saturated vapor pressure does not reach PI3 and boiling does not occur in the part whose temperature is lower than T+2. Based on the above, both fills (15) shown in Figures 3 and 4
Consider the temperature and boiling situation of the refrigerant liquid (4) during (16). If the temperature of the metal film (23) (24) is Ts, the high-temperature flow path (27) (28) hI411 is thermally isolated by the heat insulating plate (25) (26) and becomes conductive. (21) (22) Dark refrigerant liquid (4) d Due to its own natural convection, the refrigerant liquid (
4), so Ts nitsui TI>T
It is easy to establish the relationship 12>T8>T2, and therefore it is possible to always maintain the refrigerant liquid (4) in a non-boiling state between the conductive shield plates (21) and (22). On the other hand, since the metal films (23) and (24) are kept at approximately the same potential as the surfaces of both coils (15) and (16), the conductive shield plate (
An electric field will be applied only to the refrigerant liquid (4) between (21) and (22). It should be noted that although the potentials are set to be approximately the same in the above, it is taken into consideration that a voltage is generated depending on the number of turns on the surfaces of both coils (15) and (16) facing the conductive shield plates (21 and 22). However, the above voltage is sufficiently small compared to the voltage applied between both coils (15) (16), and the ordinary wire insulation (17) (18) is sufficient to withstand the above voltage. No problem.

Therefore, the refrigerant liquid (4) in the part where the electric field is applied can effectively utilize its high dielectric strength without causing boiling, and at the same time, the refrigerant liquid (9) in the part where boiling heat is transferred and its bubbles. (12) Since almost no K/'i electric field is applied, the high cooling performance can be effectively utilized without impairing the insulation performance as a transformer.
It is easy to apply to boiling-cooled high-voltage devices.

In addition, in the above embodiment, the conductive shield plate (2
1) (22) is provided opposite the high and low voltage coils (15) and (16), but if necessary, the high voltage coil (15)
It may be installed on the opposite side of the iron core (9), or furthermore, on the side of the iron core (9) opposite to the high voltage coil (15). That is, the same effect as described above can be obtained by installing the above-mentioned conductive shield plate in the heat-generating part to which an electric field is applied to the surface during operation, regardless of whether a voltage is applied or not. In addition, the heat insulating plates (25) (26) are connected to both coils (15) (16).
Depending on the conditions such as the heat generation density of ) and the shape of the flow path (27) (2B), its use may be omitted. Furthermore,
It goes without saying that the present invention can also be applied to reactors, resistors, etc. other than transformers.

As explained above, this invention is electrically connected to the surface of the heat generating part of the main body of the device, and the IIffIVc
By providing a conductive shield plate (10) arranged to allow air bubbles to flow through, the electric field within the air bubbles is suppressed to a sufficiently low level, the absolute strength is improved, and application to high voltage specifications is facilitated. It has the effect of becoming.

[Brief explanation of the drawing]

Figure 1 is an overall configuration diagram of a conventional boiling-cooled transformer, Figure 2 is an enlarged sectional view of its main parts, and Figure 3 is a boiling-cooled transformer in the Kazumi embodiment to which this invention is applied. FIG. 4 is an enlarged cross-sectional view of a part of the opposing portion of the high- and low-pressure coils. FIG. Figure, 6th
The figure is a diagram showing the relationship between the saturated vapor pressure and temperature of the refrigerant liquid. In the figure, (1) is a closed container, and (4) is an IM! compressible refrigerant liquid, (5) transformer body as Iri equipment body, (1
2) is a bubble, (15) and (16) are a high voltage coil and a low voltage coil as heat generating parts, respectively, and (21) and (22) are conductive shield plates. Note that the same reference numerals in the figures indicate the same or equivalent parts. (11) 8 258- (6HLILLI

Claims (5)

[Claims] (1) A closed container containing a condensable refrigerant liquid having insulating properties, a device body to which a voltage is applied, which has a heat generating part disposed in the refrigerant liquid and cooled by boiling heat transfer of the refrigerant liquid; By being electrically connected to the same potential part on the predetermined surface of the heat generating part, an electric field based on the voltage application is applied to the predetermined surface facing the predetermined surface and separated from the predetermined interval by the boiling heat transfer. An evaporative cooling type electric device, characterized in that it is equipped with a conductive shield plate arranged so that air bubbles generated above flow through the above-mentioned interval. (2)! 2. The boiling cooling type electrical equipment according to claim 1, wherein the electrical shielding plate is composed of a metal film and a heat insulating plate formed on the surface of the metal film. (3) The evaporative cooling electric device according to claim 2, wherein the metal film is made of a non-magnetic material. (4) The evaporative cooling type electrical equipment according to any one of claims 1 and 3, wherein the equipment body is a transformer body consisting of a winding, an iron core, and a predetermined insulator. . (5) The evaporative cooling electric device according to claim 4, wherein the heat generating portion is a winding.